A GaN based 2.2 MHz active-clamp buck converter for automotive applications

Automotive point-of-load (POL) dc-dc converters have wide input voltage range and strict EMI limitation requirements. In order to avoid the AM band interference, the switching frequency is desired to be above 2 MHz. The buck converter is widely used for this application but it has low efficiency at high switching frequency and poor EMI performance due to high dv/dt slew rate. A new active-clamp buck converter is employed in this paper, which features soft-switching for all switches, and thereby high efficiency and low EMI emission. The converter analysis, design considerations are presented. The converter is implemented with GaN FETs, due to its lower Figure-of-Merit (FOM), to further improve the efficiency. The implementation issues with GaN FETs are addressed. Then the experimental results with a 2.2 MHz prototype demonstrate superior performance of this converter.

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